1 Getting Started

1.5 Some case studies

CASE STUDY 1: Paperware company

Problem: Want forecasts of each of hundreds of items. Series can be stationary, trended or seasonal. They currently have a large forecasting program written in-house but it doesn’t seem to produce sensible forecasts. They want me to fix it.

Additional information

Program written in COBOL making numerical calculations limited. It is not possible to do any optimisation.
They employ no statisticians and want the program to produce forecasts automatically.

CASE STUDY 1: Paperware company

Methods currently used

A: 12 month average
C: 6 month average
E: straight line regression over last 12 months
G: straight line regression over last 6 months
H: average slope between last year’s and this year’s values. (Equivalent to differencing at lag 12 and taking mean.)
I: Same as H except over 6 months.
K: I couldn’t understand the explanation.

CASE STUDY 2: PBS

The Pharmaceutical Benefits Scheme (PBS) is the Australian government drugs subsidy scheme.

Many drugs bought from pharmacies are subsidised to allow more equitable access to modern drugs.
The cost to government is determined by the number and types of drugs purchased. Currently nearly 1% of GDP.
The total cost is budgeted based on forecasts of drug usage.

CASE STUDY 2: PBS

In 2001: $4.5 billion budget, under-forecasted by $800 million.
Thousands of products. Seasonal demand.
Subject to covert marketing, volatile products, uncontrollable expenditure.
Although monthly data available for 10 years, data are aggregated to annual values, and only the first three years are used in estimating the forecasts.
All forecasts being done with the function in MS-Excel!

CASE STUDY 3: Car fleet company

Client: One of Australia’s largest car fleet companies

Problem: how to forecast resale value of vehicles? How should this affect leasing and sales policies?

Additional information

They can provide a large amount of data on previous vehicles and their eventual resale values.
The resale values are currently estimated by a group of specialists. They see me as a threat and do not cooperate.

CASE STUDY 4: Airline

Problem: how to forecast passenger traffic on major routes?

Additional information

They can provide a large amount of data on previous routes.
Traffic is affected by school holidays, special events such as the Grand Prix, advertising campaigns, competition behaviour, etc.
They have a highly capable team of people who are able to do most of the computing.